Equipment qualification and materials qualification are essential activities for the nuclear industry to demonstrate that new and existing plant equipment will operate safely in all conditions and also shut down safely in fault conditions, writes Sean Weller
New nuclear power plants cost up to $25 billion to build. But, midway through construction or once up and running, they could suffer considerable delays or even temporary shutdowns because of a fault in a seemingly insignificant sub-assembly item.
For example, the pumps and valves essential for safe operation of the cooling system rely on elastomer 'O' ring seals to maintain the equipment's integrity. If these seals fail, they could curtail the operation of the plant or significantly delay its life extension.
To mitigate this risk for reactor vendors and operators, Amec Foster Wheeler has carried out extensive accelerated ageing tests on 'O' ring seals by simulating the wear and tear caused by heat, mechanical stresses and radiation, as well as accident conditions. Batch testing of these easily overlooked ancillary items revealed discrepancies in manufacturing quality and a wide variance in performance.
This underlines the importance of equipment qualification (EQ) and materials qualification (MQ). They are essential activities for all high integrity industries, not just nuclear, to demonstrate that new and existing plant equipment, whether mechanical, electromechanical, electrical or electronic, will operate safely in all conditions and also shut down safely in fault conditions.
In the nuclear industry, EQ is a regulatory requirement which must be satisfied in order to obtain and maintain a licence to operate. Failure to carry out EQ programmes that meet expected standards and relevant good practice can lead to significant delays, which in turn may drive up the cost of commissioning new plants or resuming operations.
EQ is often considered as a qualification process to establish that a manufactured component or system is fit for purpose. In fact, the EQ process is fully applicable from design and materials selection right through to life extension. The International Atomic Energy Authority (IAEA) defines this lifecycle as the 'Four Phases of EQ' (see Figure 1).
Incorporating EQ requirements into the design stage will inevitably help ensure that downstream EQ programmes go to plan and that equipment qualifies right first time.
EQ assessments, tests and justifications can take many months to complete and so early EQ planning is essential. Testing programmes typically include thermal, climatic and mechanical tests as well as irradiation, seismic and electromagnetic compatibility (EMC) testing. Thermodynamic accident condition testing, such as for loss of coolant accidents (LOCA) or high energy line breaks (HELB), is also typically required, either on the component or full scale equipment level.
EQ programmes can often be optimised by testing families of components, grouping similar equipment and components with similar functionality and materials, so that one piece within the family can be tested and justified as representative of the entire family.
Although a lot of work is required to group a family accurately, the time and effort invested can yield quite considerable EQ savings in both time and costs. Furthermore, applying condition monitoring techniques to an item of equipment at an early stage in its lifecycle can allow the EQ test programme to be streamlined. High quality lifecycle information can support the case for extending a given item of equipment, and therefore the plant, beyond its design life and thereby adding many millions of pounds to the value of its lifetime electricity output.
To yield such savings through a programme approach and to help ensure local regulator acceptance, it may make sense to work with an EQ supplier who is capable of managing the overall EQ programme, particularly a supplier with an established track record of successfully helping to qualify and maintain nuclear power plants and ensuring that they exceed electricity generation targets.
Amec Foster Wheeler has formed an alliance with Element Materials Technology, Tecnatom and TUV Rheinland to offer EQ and MQ services for nuclear sites in the UK and Europe.
Together the four companies, which individually already support many power plants and other nuclear licensed sites around the world, have formed the EQ Services Alliance (EQSA) so that customers can benefit from their vast collective global experience, specialist testing facilities and qualification expertise.
Greg Willetts, Vice-President for Consultancy and Defence at Amec Foster Wheeler's Clean Energy business, says: "Our collective capability and expertise means that EQSA can meet all of our customers' EQ and MQ needs on new build or modification projects.
"EQSA is dedicated to ensuring that the new build supply chain and existing operators can correctly qualify safety critical components right first time in order to meet UK and European regulatory expectations while helping to avoid delays and unforeseen costs as the project develops.
"We are supporting customers on materials selection and preparation of qualification plans as well as analysis and testing - all designed to establish, preserve and upgrade required equipment qualifications."
Examples of services offered by EQSA include design support, materials selection, desktop/physical analysis, operating experience, ageing and thermodynamic accident conditions/design basis event testing (such as loss-of-coolant accident), seismic testing and analysis, CE marking test and certification, accelerated ageing tests on materials and equipment and testing for mechanical and corrosion resistance.
Dr Sean Weller has a doctorate in materials engineering.
As Equipment Qualification Lead Consultant at Amec Foster Wheeler, his expertise covers qualification test programme strategy, qualification of suppliers and their products or equipment, and review of manufacturing qualification documentation. He can be contacted for further information at email@example.com